This invention relates to aquarium filters and more particularly to an undergravel aquarium aerating and filtering system for aquarium tanks.
There are presently available numerous types and forms of aquarium filters. Most of these simultaneously provide for filtering of the decontaminated water from the fish tank, and at the same time provide the necessary aeration of the water to ensure an adequate supply of dissolved air into the water. Most of the aquarium filters include air pumps which bubble air into a housing and permit the air to pass out of outlet pipes. Water from the tank is sucked into the enclosure and filtered, and the decontaminated water is caused to flow out of the outlet tube together with the air, thereby providing an airlift of clean water which is filtered and aerated.
One type of aquarium filter devices is the bottom aquarium filter which is placed over the gravel near the bottom of the tank. These filters use filtering material directly in the filter housing, such as charcoal, fiberglass, etc. The decontaminated water enters into the filter housing and passes through the filter material within the housing. The decontaminated water is then air lifted out of the housing by means of the flow of air. Another type of aquarium filter is known as the undergravel filter device. In such filters, the filter is placed under the gravel bed at the bottom of the aquarium tank. A compartment is formed between the housing and the bottom of the aquarium tank. Slots are formed in the housing which are small enough to permit the water to pass into the enclosure while preventing the gravel from passing through these openings. Air is pumped to the enclosure and is permitted to leave through an outlet pipe. As the air leaves, it causes a suction whereby water is drawn from the tank through the gravel into the enclosure, and passes out of the outlet means together with the air.
In the latter type of filters, the aquarium gravel bed serves as the filter material and bacteria can convert the sewage and other decontamination waste products into non-toxic matter largely in the form of gaseous matter. Alternately, as the waste accumulates in greater amounts than can be converted, the gravel can be taken out, washed, and cleaned and then returned back to again form the gravel bed over the filter.
However, existing undergravel filter devices have not adequately solved problems which are peculiarly inherent to such undergravel filter devices. By way of example, one problem existing with undergravel filter devices concerns their size. When using a bottom aquarium filter which is placed on top of the gravel, this filter can be placed in any portion of the aquarium tank which has adequate size to accommodate the filter housing. For example, in bowl shaped aquarium tanks, there exists a wider portion near the center of the tank. The bottom aquarium filter can therefore be placed at this wider portion in order to accommodate a large size filter. Additionally, since the bottom aquarium filter can be moved about and placed at any appropriate place in the tank, various shapes of filters can be utilized to accommodate any particular shape of the aquarium tank. In narrow tall tanks, a bottom aquarium filter can be utilized which is narrow and tall and because of its height will provide sufficient filtering capacity. If the aquarium tank is shallow and wide, a flattened type of bottom aquarium filter can be placed on top of the gravel whose width will be large enough to provide the needed filtering capacity.
However, in undergravel type filters, there exits a space limitation. Since this filter must be placed under the gravel, the height of the filter housing is generally limited by the thickness of the gravel bed. This thickness is generally small for all types of aquarium tanks. To provide enough filtering capacity, the area must therefore be made wide. A given filter housing may be adequate for large aquarium tanks, but its size may be too large for smaller tanks. Alternately, if only a small sized undergravel filter is manufactured, there will be insufficient filtering capacity for a large size tank. Accordingly, one problem that has not been heretofore faced is to provide an undergravel filter device which can be useful for various sized aquarium tanks, both large and small.
Another problem unique to the undergravel filter device concerns the flow of air into the water compartment. In such filters, the water compartment is formed between the tank floor and the top plate of the filter housing. It is into this water compartment that the tank water must enter. The air must then be pumped into this compartment. Furthermore, the air must be provided in appropriate supply and in proper direction to cause sufficient suction throughout this water compartment to thereby permit filtering of the water throughout the entire surface area of the filter housing. Some prior art devices have attempted to direct the ingressed air only beneath the gravel and into the water compartment. However, the air will then have a tendency not to provide sufficient suction within the entire area of the filter. Other prior devices have formed a vertical tube directly over the water compartment having adjacent inlet and egress means. However, the air will then immediately return up the outlet pipe without providing sufficient opportunity to bring therewith the filtered water from the water compartment. Accordingly, such undergravel filter devices have generally not been as efficient or satisfactory as bottom aquarium filters which, as set forth above, are placed on top of the gravel bed.
A further problem existing with undergravel filter devices concerns the packaging of the equipment. The equipment of a filter generally includes the filter housing, the air pump, the air hose, the line cord connected to the air pump, and any other pipes needed for inlet and outlet of the air and water. With bottom aquarium filters placed on top of the gravel, the filter housing is of relatively large shape, typically of a rectangular or triangular configuration, and most of the parts of the complete filter system can be placed directly within the filter housing. However, the undergravel filter device has a filter housing which is of comparatively shallow depth and relatively wide area and accordingly makes it inconvenient to provide a compact package of all the components necessary for a complete aquarium filter and aerating system.